This invention relates generally to heating and/or air conditioning systems, and is specifically directed to a heating and air conditioning system in which heat exchange is accomplished through the use of geothermal ground coils which are vertically inserted into the ground.
In air conditioning systems commonly is use, and in heat pump systems in particular, heat exchange between a refrigerant contained within the system and the environment is required. Most commonly, this heat exchange has been accomplished by means of ambient air, wherein the refrigerant is directed to an outdoor coil and heat exchange between the refrigerant contained within the coils is made with the outside air.
The problem associated with heat exchange with outside air is the inconsistency of the temperature of the outside air. Particularly with heat pumps, since heat for the heating cycle is obtained from the outside air, the system loses its efficacy and efficiency as the outside temperature drops, since there is less heat in the air which can be extracted for the purpose of indoor heating. This problem is compounded due to the fact that as the temperature drops, additional heat is needed to heat the building.
To overcome the problems associated with heat exchange with the outside air, water and geothermal means have been employed for heat exchange. In the water system, heat exchange within the refrigerant contained within the system is accomplished by exposing refrigerant contained within the coil to quantities of water, which is generally passed in a dynamic fashion across the coils. This system requires large quantities of water, and ground water is usually employed. Limitations in this system include the availability of ground water which can be efficiently and cost-effectively obtained in sufficient quantities to achieve the desired and required heat exchange.
It has previously been recognized that geothermal heat exchange is potentially an efficient and effective way of achieving heat exchange in heating and air conditioning systems, and especially heat pump type systems. Since the ground temperature is relatively constant at about 68 degrees F. at a depth below the frost line, the available heat is constant. However, a problem which has been associated with such systems is the means and manner in which the heat exchange coils, or outdoor coils, are placed into the ground to achieve geothermal heat exchange.
It is preferred to place the geothermal outdoor coils into the ground in a vertical fashion. Installation may be easily accomplished by drilling or boring holes into the ground, into which the vertical geothermal outdoor coils may be placed. The coils may quickly and easily be placed into the ground to a depth with is sufficient to overcome ground freezing problems associated with colder climates.
Heretofore, the reason that placing coils into the ground in a vertical fashion has not been workable is due to the fact that when sufficient refrigerant is placed into the system to achieve maximum efficiency on both the heating and cooling cycles, the refrigerant as it condenses in the ground coils, causes a liquid refrigerant build-up. The compressor is unable to properly move the refrigerant through the system when the liquid refrigerant settles within the ground coils, making the system unworkable. Damage to the compressor can occur when the compressor forces liquid refrigerant into the intake of the compressor, since compressors for such systems ar designed for receiving and compressing gases.
In the prior art, to overcome the problem associated with vertical outdoor geothermal coils, the coils have been placed into the ground in a horizontal fashion. Placing the coils into the ground in a horizontal fashion alleviates the problem of liquid refrigerant build-up, since there is not a low point which the refrigerant seeks, but requires a vast amount of available ground to achieve the proper heat exchange, and requires the excavation of sufficient land to place enough ground coils to achieve sufficient heat exchange. In colder climates, this excavation must also be to a sufficient depth to place the coils for proper heat exchange. In short, placing the geothermal coils in a horizontal fashion is more difficult, expensive, and requires much more available ground than does placing of the coils into vertical holes.